DE69320672T2 - Color beam recording apparatus and method and recording material - Google Patents

Abstract

An ink jet textile printing apparatus for performing the recording by reading an original image created by the designer, converting the original image into original data represented by an electric signal, retrieving the original data for the processing to be output as image data, and recording data on the cloths based on the image data. The ink jet textile printing apparatus has a first ink jet recording head (31) provided upstream of the recording, and a second ink jet recording head (31') provided downstream thereof, and is provided with a drying unit (35) between both recording heads, whereby high-quality recorded image with less bleeding can be obtained by recording on said recording area again with the second ink jet recording head (31') after drying a recording area on the cloths recorded by the first ink jet recording head (31) with the drying unit (35).

Description

The invention relates to an ink jet recording method and apparatus and recording medium therefor for recording the image on a recording medium such as cloth made of cotton and silk and the like by scanning a recording head relative to the recording medium.

Typical of the conventional textile printing apparatus for recording on fabric as a recording medium is a textile screen printing apparatus for directly performing printing on the fabric using a screen printing plate. In performing textile printing using such a textile screen printing apparatus, first, for an original image to be printed, a silk screen printing plate for each color used in that original image must be prepared and placed in the textile screen printing apparatus, and the ink must be transferred to the fabric through the meshes of the silk screen printing plate.

The textile screen printing apparatus described above has a problem in that a large number of processes and days are required to prepare the silk screen printing plates and to perform the operations such as adjusting the ratio of color inks and aligning the silk screen printing plate for each color. Furthermore, the apparatus also has an additional problem in that the mechanism becomes larger in proportion to the number of colors used, a large installation space is required, and storage space for the silk screen printing plates is necessary.

On the other hand, inkjet recording has a much higher resolution than conventional textile screen printing, which allows printing of high-quality patterns with gradations. And it has a feature that much higher productivity can be expected using a multi-nozzle head with several hundreds to thousands of nozzles.

Due to the nature of recording with the ink ejected through tiny ink jet nozzles, it is necessary to use low viscosity (thin) ink. Accordingly, dark patterns cannot be recorded. If a large amount of ink is ejected, a darker pattern will be obtained, but the ink may smear on the fabric, so that a high-quality pattern cannot be created.

Also, due to a large number of nozzles used in parallel, it is difficult to produce flawless images due to unevenness, deviation and white streaks that may occur due to accidental mis-discharge during recording, depending on the characteristics of the nozzle. This is a serious problem in machines in industrial use that produce tens to hundreds of meters of printed output at a time in continuous operation.

Light color is represented by applying ink drops sparingly, which often results in the roughness of the image. In particular, if one tries to increase the diameter of the nozzle or ink droplets in order to avoid the disadvantage described above, this means that the resolution is reduced, which results in even more noticeable roughness.

Some treatments are effectively applied immediately before recording because they are unstable on the tissue, but such agents cannot be used in the conventional process.

On the other hand, an ink jet recording apparatus is an apparatus for carrying out dot-by-dot recording by ejecting ink droplets from nozzles of the recording head onto a recording medium, and is effective in terms of apparatus structure and running cost. An example of such a recording apparatus is one in which recording or printing is carried out by sequentially scanning a recording head having a row of nozzles arranged in a predetermined width (about 16 mm) lengthwise and widthwise relative to the recording medium.

However, there is some dispersion in the amount or direction of the ink ejected from each nozzle of the ink jet recording head, and this dispersion may produce noticeable streaks. For this reason, there was a problem that streaks or spots periodically appeared on the recorded image in a width of the recording head, deteriorating the image quality. There was also a problem that these spots may change with time over a long period of recording.

Furthermore, a problem occurred in that when contaminants such as dirt or ink adhering to the nozzle surface of the recording head prevented normal ink ejection from the nozzles (hereinafter referred to as mis-ejection), line errors in the image could occur, thereby degrading the image quality.

To solve these problems, it is conceivable to print a predetermined pattern and judge it visually or by means of a reader in order to correct the unevenness with the head based on the information obtained.

However, if the execution of the correction operation is left to the judgment of the operator, the correction roperation may sometimes give rise to undue effect. Furthermore, in this case no action is taken against the misemission.

Furthermore, it is necessary to check the phenomenon of causing such deterioration of image quality at any time and to carry out the correction appropriately, but when a long roll of recording sheet is used, printing on a very long recording sheet (e.g., 100 m long or more) can be carried out simultaneously at one time, so that the mis-ejection unevenness during printing becomes a big problem and the correction becomes a very difficult task. There also occurs another problem that in the case where the long roll of recording sheet is made of a woven fabric, fine fluffy fibers are attached around the nozzles of the recording head, so that the possibility of causing the mis-ejection is much higher than in the case where the recording sheet is paper or the like.

In addition, when the recording medium was fabric made of, for example, cotton or silk and the like, a great problem arose in that even when a predetermined pattern was recorded on the recording medium and judged visually or with a reader to correct the unevenness with the head on the basis of the information obtained, the bleeding of the ink could occur and due to the unevenness on the surface of the recording medium caused by the texture of the fibers, the predetermined recorded pattern could not be read accurately, so that the accurate detection of the ejection state of the recording head was difficult.

Conventionally, an ink jet printer having a plurality of multi-nozzle heads for recording the image on a recording medium with these ink jet heads is well known. In such a printer, in order to adjust the alignment of the To perform recording position adjustment with a plurality of heads, an image having a predetermined pattern such as a checkered pattern is printed on a recording sheet using the plurality of ink jet heads, the printing result is visually judged or read using the reading device such as a scanner, and the deviation of the recorded pattern is calculated to determine the deviation of each ink jet head. Based on the deviation thus obtained, adjustment of the recording position is carried out according to the arrangement position of the ink jet head by changing the reading timing of each memory for storing the image data to be recorded by each ink jet head.

However, the conventional alignment method as described above was an alignment method when a plurality of ink jet heads were arranged transversely to the scanning direction of the carriage, but when a plurality of recording heads were arranged perpendicularly or at right angles to the scanning direction of the carriage, the positional deviation was adjusted only mechanically.

In view of the above-described disadvantages of the prior art, the present invention has been achieved on the basis of new aspects which were not conventionally foreseeable.

It is the object of the invention to provide an ink jet recording apparatus and method which does not require the manufacture of screen printing plates or the mixing of each color ink when the recording on fabrics made of a material such as cotton or silk or paper can be realized in a smaller size than previously.

Japanese Patent Document No. JP-601015546 describes an inkjet recording apparatus for recording an image on an overhead projection screen by scanning Recording heads which are movable relative to the overhead projection film. The device has a first inkjet recording head which is arranged in an access position with respect to the transport direction of the recording medium, and a second inkjet recording head which is arranged in an exit position. The device can also be used to print on normal paper, in which case only one of the recording heads is controlled. According to the invention, an inkjet recording device with the features of claim 1 is shown. Furthermore, according to the invention, an inkjet recording method according to claim 11 is shown.

It should be noted that the term "recording" as used in the present specification and claims is to be understood to mean "printing" and in a broader sense means forming an image on a recording medium such as fabric made of cotton, silk and the like and paper. It should also be noted that the term "recording" does not limit the scope of the invention.

Fig. 1 shows a block diagram of a structure of an inkjet textile printing device according to the invention,

Fig. 2 shows a cross-sectional view of a structure of an image recording unit,

Fig. 3 is a perspective view showing the details of a structure of an ink jet recording unit,

Fig. 4 is a plan view showing the positional relationship between the inkjet recording unit and a tissue transport unit,

Fig. 5 shows a plan view of a structure of an image reading device,

Fig. 6 is a view for explaining the image reading operation in the image reading device,

Fig. 7 is a block diagram showing a structure of a control system in an inkjet textile printing apparatus,

Fig. 8 shows a block diagram of a structure of a head correction unit,

Fig. 9 is a diagram explaining a correction table for use in head correction,

Fig. 10 is a diagram for explaining a method for correcting density unevenness,

Fig. 11 shows a block diagram of a circuit structure of an inkjet recording unit and a tissue transport unit,

Fig. 12 shows a timing chart of the interrelationship between each signal in a control unit,

Fig. 13 is a perspective view of the main part of a recording unit on an enlarged scale,

Fig. 14 shows a diagram explaining the overlapping recording,

Fig. 15 shows a view of an embodiment of a recording device according to the invention,

Fig. 16 is a view showing the surroundings of a recording head shown in Fig. 15,

Fig. 17 shows a view of a monitoring device shown in Fig. 16,

Fig. 18 shows a diagram of a sensor output of the monitoring device,

Fig. 19 shows a flow chart of the operation sequence in the embodiment,

Fig. 20 is a view showing a structure of a main part of an ink jet printer in an embodiment,

Fig. 21 is a block diagram showing a structure of a main control unit of the inkjet printer in an embodiment,

Fig. 22 is a block diagram showing a structure of a main control unit of the ink jet printer of another embodiment,

Fig. 23 is a diagram showing a storage plan of a frame memory for storing the recording data corresponding to each band,

Fig. 24 is a diagram for explaining a circuit configuration for use in controlling the reading start position of the recording data from the frame memory,

Fig. 25A and Fig. 25B showed views of printing examples of the longitudinal alignment adjustment pattern in an embodiment of the ink jet printer,

Fig. 26 is a view showing an example in which the recording point positions of the upper and lower heads coincide,

Fig. 27 is a diagram showing an output example (R component) from the sensor when the recording dot positions of the upper and lower cyan heads are the same,

Fig. 28 is a diagram showing an output example (G component) from the sensor when the recording dot positions of the upper and lower cyan heads are the same,

Fig. 29 is a diagram showing an output example (B component) from the sensor when the recording dot positions of the upper and lower cyan heads coincide,

Fig. 30 is a view showing a recording dot example when the recording dot position of an upper cyan head deviates by one pixel,

Fig. 31 is a diagram showing an output example (R component) of the sensor in a state as shown in Fig. 30

Fig. 32 is a diagram showing an output example (G component) of the sensor in the state shown in Fig. 30 ,

Fig. 33 is a diagram showing an output example (B component) of the sensor in the state shown in Fig. 30 ,

Fig. 34 is a view showing a dot recording example when the recording dot position of the upper cyan head deviates one pixel downward,

Fig. 35 is a diagram showing an output example (R component) of the sensor in a state as shown in Fig. 34

Fig. 36 is a diagram showing an output example (G component) of the sensor in the state shown in Fig. 34 ,

Fig. 37 is a diagram showing an output example (B component) of the sensor in the state shown in Fig. 34 ,

Fig. 38 is a flow chart showing a pattern recording and reading process for alignment adjustment in an embodiment of the inkjet printer,

Fig. 39 is a diagram showing a result (R component) of reading the recorded image when the patterns recorded by a lower cyan head and an upper magenta head match,

Fig. 40 is a diagram showing a result (G component) of reading the recorded image when the patterns recorded by the lower cyan head and the upper magenta head match,

Fig. 41 is a diagram showing a result (B component) of reading the recorded image when the patterns recorded by the lower cyan head and the upper magenta head match,

Fig. 42 is a diagram showing a reading result (R component) when the dot recorded by a magenta head deviates one pixel upward in the patterns recorded by a lower cyan head and an upper magenta head,

Fig. 43 is a diagram showing a reading result (G component) when the dot recorded by the magenta head deviates one pixel upward in the patterns recorded by the lower cyan head and the upper magenta head,

Fig. 44 is a diagram showing a reading result (B component) when the dot recorded by the magenta head deviates one pixel upward in the patterns recorded by the lower cyan head and the upper magenta head,

Fig. 45 shows a diagram of a reading result (R component) when the dots in the patterns recorded by a lower cyan head and an upper yellow head match,

Fig. 46 shows a diagram of a reading result (G component) when the dots in the area formed by the lower cyan head and the upper yellowhead recorded patterns,

Fig. 47 shows a diagram of a reading result (B component) when the dots in the patterns recorded by the lower cyan head and the upper yellow head match,

Fig. 48 is a diagram showing a reading result (R component) when the dot recorded by a yellow head deviates one pixel upward in the patterns recorded by a lower cyan head and an upper yellow head,

Fig. 49 is a diagram showing a reading result (G component) when the dot recorded by the yellow head deviates one pixel upward in the patterns recorded by the lower cyan head and the upper yellow head,

Fig. 50 is a diagram showing a reading result (B component) when the dot recorded by the yellow head deviates one pixel upward in the patterns recorded by the lower cyan head and the upper yellow head,

Fig. 51 shows a diagram of a reading result (R component) when the dots in the patterns recorded by a lower cyan head and an upper black head match,

Fig. 52 shows a diagram of a reading result (G component) when the dots in the patterns recorded by the lower cyan head and the upper black head match,

Fig. 53 shows a diagram of a reading result (B component) when the dots in the patterns recorded by the lower cyan head and the upper black head match,

Fig. 54 shows a reading result (R component) when the dot recorded by the black head deviates one pixel upward in the patterns recorded by the lower cyan head and the upper black head,

Fig. 55 shows a reading result (G component) when the dot recorded by the black head deviates one pixel upward in the patterns recorded by the lower cyan head and the upper black head,

Fig. 56 shows a reading result (B component) when the dot recorded by the black head deviates one pixel upward in the patterns recorded by the lower cyan head and the upper black head, and

Fig. 57 is a view showing a schematic structure of an ink jet printer in another embodiment of the present invention.

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

(First embodiment)

Fig. 1 shows a block diagram of a structure of an ink jet textile printing apparatus of an embodiment of the present invention. This ink jet textile printing apparatus is constructed as a system which essentially comprises: an image reading device 1 for reading an original image created by a pattern designer and converting the original image into original data represented by an electric signal, an image processing unit 2 for processing the original data from the image reading device 1 which is output as image data, and an image recording unit 3 for recording on fabric based on the image data created by the image processing unit 2. In the image reading device 1, the original image is read by a CCD image sensor. The image processing The ink jet recording unit 2 generates data for driving an ink jet recording unit A-2 (Fig. 2) to eject four color inks of magenta (M), cyan (C), yellow (Y) and black (Bk) from original input data as described below. The creation of the data includes image processing for reproducing the original image as ink dots, color distribution to determine tone, changing the layout, editing or selecting the image size such as enlargement or reduction. The ink jet recording unit A-2 carries out recording in such a manner as to eject the fine ink droplets onto a recording medium (cloth in this embodiment) to make them adhere to the recording medium.

First, the structure of the image recording unit 3 will be described below. Fig. 2 shows a cross-sectional view of a structure of the image recording unit 3, Fig. 3 shows a perspective view of the details of a structure of the ink jet recording unit A-2 included in the image recording unit 3, and Fig. 4 shows a plan view showing the positional relationship between the ink jet recording unit A-2 and the web transport unit.

The textile printing apparatus (printer) of this embodiment basically comprises a fabric supply unit B for supplying the fabric wound on a roll and pretreated for textile printing, a main unit for printing with an inkjet head while feeding the fabric accurately, and a take-up unit C for taking up the printed fabric after drying. And the main unit A comprises a precision fabric supply unit A-1 having a printing plate and an inkjet recording unit A-2.

The pretreated fabric 36 from the roll is fed to the fabric feed unit and fed to the main unit A. In the main unit, a thin endless belt 37, which is ex akt is driven stepwise to loop around a drive roller 47 and a drag roller 49. The drive roller 47 is directly driven stepwise by a high resolution stepping motor (not shown) to feed the tape stepwise. The fed fabric 36 is pressed by a pressure roller 40 onto the surface of the tape 37, which is supported on the back by the drag roller 49, and is held thereto by adhesion.

The fabric 36 fed stepwise through the belt is placed on the back of the belt in a first printing unit 31 by means of a printing plate 32 and printed on the front of the belt by an ink jet head 9. Each time a line of printing is completed, the fabric is fed a predetermined step and is then dried by the heat of a heating plate 34 on the back of the belt and by the hot air fed to its surface through a hot air duct 35. Then, in a second printing unit 31, overlap printing is carried out in the same manner as in the first printing unit.

The printed fabric is peeled off and dried again by a post-drying unit 46 similar to the heating plate and hot air duct as described above, and passed through a guide roller 41 to be wound up on a winding roll 48. The wound up fabric is taken out of the main apparatus and subjected to post-treatment such as dyeing, cleaning and drying in the batch processing to provide the products.

Fig. 3 shows one of the printing units in the ink jet recording unit A-2 for better understanding.

The ink jet recording unit A-2 essentially comprises: a frame 6, two parallel guide rails 7, 8 which are arranged on the frame 6, an ink jet head 9, a head carriage 10 on which the ink jet head 9 is arranged, an ink supply device 11, an ink carriage 12 on which the ink supply device 11 is arranged, a head regeneration device 13 and an electrical system 5.

The ink jet head 9 has a plurality of nozzle rows and a converting means for converting an electric signal into an ink ejection energy, and has a mechanism for selectively ejecting the ink through the nozzle rows according to a driving image signal from the image processing unit 2. Here, a method of ejecting the ink in the ink jet head 9 is not different from the method of the ink jet head for use in the conventional ink jet recording apparatus using paper as the recording medium. In this embodiment, in order to reproduce arbitrary colors, four color inks of magenta (M), cyan (C), yellow (Y) and black (Bk) are ejected from the ink jet head 9 as described above. These four color inks are ejected by the recording heads 117 to 120 (Fig. 7) arranged in the ink jet head 9, respectively. Each recording head 117 to 120 is provided with a plurality of nozzles (e.g., 256 lines) for ejecting a respective color ink through these nozzles.

The ink supply device 11 is for holding four color inks of M, C, Y and Bk and supplying the required amounts of ink to the ink jet head 9, and comprises an ink tank and an ink pump (not shown). The ink supply device 11 and the ink jet head 9 are connected via an ink supply pipe 19, and normally, due to capillary action, the amount of ink to be ejected from the ink jet head 9 is automatically supplied to the ink jet head 9. In the head recovery operation as described below, the ink is forcibly supplied to the ink head 9 using an ink pump (not shown). This ink jet head 9 and the ink supply device 11 are arranged on the head carriage 10 and the ink carriage 12, respectively, for mutual movement. by a drive device not shown along the guide rails 7, 8.

The head recovery device 13 is arranged in opposition to the ink jet head 9 in a home position to maintain the stability of the ink jet head 9, and specifically performs the following operations. That is, in order to prevent the evaporation of the ink from the nozzles of the ink jet head when not in operation, a capping unit 24 allows capping of the ink jet head 9 in the home position to be carried out (capping operation). Before starting image recording, an operation of forcibly discharging the ink through the nozzles by pressing the ink channels inside the ink jet head 9 using the ink pump (pressure recovery operation) is required to remove bubbles or dirt inside the nozzles, with the head recovery device 13 serving to drain the ejected ink.

The electrical system 5 includes a control unit for executing sequence control of the entire ink jet recording unit 1 and a power supply unit and is arranged on the frame 6.

While the structure of the ink jet recording unit A-2 has been described, it will be understood that the ink jet recording unit 1 is supported on the frame 1051, 1052 of the cloth transport unit 43 via a rail (not shown) as shown in Fig. 4 so as to be movable in a direction away from the platen 32 by releasing the safety device (not shown). Finally, a working space is provided between the transport belt 37 of the cloth transport unit 43 and the ink jet recording unit A-2 to facilitate the handling of the cloth 36 on the transport belt 37 when the abnormal condition occurs. As shown in Fig. 4, the capping position of the ink jet head 9 is located outside a frame 1051 of the cloth transport unit 43 to facilitate the maintenance of the inkjet head 9 and to facilitate the refilling of ink by the operator.

The image reading device 1 will be described below. Fig. 5 shows a plan view of a structure of the image reading device 1. The image reading device 1 belongs to a type of so-called image scanning device in which an original image is converted into an electric signal (original data) by a CCD unit 18.

The CCD unit 18 has a CCD 16 and a lens 15 for forming an image on the CCD 16 and is freely movable on a main direction rail 54. At one end of the main direction rail 54, a pulley 51 and a main scanning motor 50 are arranged, which is connected to the pulley 51. At the other end of the main direction rail 54, another pulley 52 is arranged, with a wire 53 stretched between both pulleys 51, 52 and connected to the CCD unit 18. This main scanning motor 50, the pulleys 51, 52 and the wire 53 form a drive system in a main scanning direction in which the CCD unit 18 is driven to move it to any position on the main direction rail 54.

The main direction rail 54 is slidably arranged at both ends opposite two sub-direction rails 65, 69 which are arranged at right angles to the main direction rail 54. The two sub-direction rails 65, 69 are parallel to each other and have the same length, the portion between the two sub-direction rails 65, 69 being a reading area 77. Each sub-direction rail 65, 69 is provided with a pulley 76, 68 at one end thereof and a pulley 67, 71 at the other end thereof. For each sub-direction rail 65, 69, a wire 66, 70 is arranged to extend around the pulleys 76, 67 and 68, 71 at both ends, each wire 66, 70 being connected to a respective end portion of the main direction rail 54. The pulleys 76, 68 which each arranged at one end of the sub-direction rails 65, 69 have a fixed connection with a shaft 72, while the pulleys 67, 71 are fixedly arranged at the other ends of the other shaft 73. These two shafts 72, 73 are arranged parallel to each other and to the main direction rail 54 and are rotatable thereabout. A sub-scanning motor 60 is arranged at an end portion of a shaft 72. These shafts 72, 73, the sub-direction rails 65, 67, the pulleys 76, 67, 68, 71 and the sub-scanning motor 60 form a drive system in a sub-scanning direction, wherein the main direction rail 54 is movable in one direction along the sub-direction rails 65, 69 by driving the sub-scanning motor 60.

Essentially, an original glass plate 17 is arranged over an entire area of the reading area 77, which is arranged in the opposite position to the CCD unit 18. The end section of the reading area 77 is the correction area 78.

With such a structure, the image reading device 1 can move the CCD unit 18 to any position in the reading area 77 by driving the main scanning motor 50 and the sub-scanning motor 60. In this case, in order to detect the CCD unit to move it to the home position (an origin position of the coordinates for reading) in the reading area 77, home position sensors 56, 58 are arranged at the other ends of the main direction rail 54 and a sub-direction rail 65, respectively. In the embodiment shown in Fig. 5, the home position is provided corresponding to the correction area 78.

Referring to Fig. 6, the image reading operation of the image reading device will be described below.

The image reading operation first begins with the movement of the CCD unit 18 to the home position HP in the correction area 78 and with the initiation of the reading operation of a complete original arranged on the original glass plate 17.

Before scanning the original, setting of necessary data for processing such as shadow correction, black level correction and color correction is carried out in the correction section 78. Thereafter, scanning of the CCD unit 18 is started in a main scanning direction (a transverse direction as shown) by the main scanning motor 50 along a direction shown by the arrow in the figure. When the reading operation of a first area as indicated by (1) is completed, movement of the CCD unit in a sub-scanning direction to the correction section 78 for an area indicated by (2) adjacent to the area indicated by (1) is carried out by reversing the rotation direction of the main scanning motor 50 as well as driving the sub-scanning motor 60. Thereafter, as with the area (1), processing such as color correction is carried out. B. Shadow correction, black level correction and color correction are carried out as required, and the original is read while the CCD unit 18 is moved in the main scanning direction. Note that in Fig. 6, reference character P indicates an area to be read by one scan and Q denotes an area practically readable by one scan.

By repeating the above-described scanning, the reading operation is carried out for the entire area or the areas (1) to (7) in an embodiment of Fig. 6, and after the reading operation for the end area or the area (7) is completed, the CCD unit 18 is returned to the home position HP. From the relationship between the size of the typical original and the width readable by the CCD unit 18 in one scan, more scans can actually be carried out in this embodiment, but in this embodiment, the operation has been simplified to facilitate understanding.

If the reading operation described above is carried out at the same magnification, the area readable by the CCD unit 18 by one scan is wider than the actual tially read as shown in Fig. 6. This is because this image reading device 1 has a characteristic of variable magnification and reduction. For example, when the area recordable by the ink jet head 9 at one time is 256 dots in size, the image information of the area of 512 dots which is equal to 2 x 256 dots is required to perform a 50% reduction operation. Accordingly, the image reading device 1 has a characteristic of reading and outputting the image information for an arbitrary image area by a reading operation in the main scanning direction.

Referring to Fig. 7, the description will be given below of the structure of the image processing unit 2. Since the image processing unit 2 operates in cooperation with the respective control systems of the image reading device 1 and the image recording unit 3, the control systems of the image reading device 1 and the image recording unit 3 will also be described below.

The image processing unit 2 is provided with a control circuit 111 which is a control circuit for data transmission and recording with a host system (not shown) such as a computer. The image reading device 1 and the image recording unit 3 are each provided with control units 102, 121 or control circuits for carrying out control thereof. Each of these control units 102, 111 and 121 is provided with a microprocessor, a program ROM, a data memory and a communication circuit. The control unit 102 and the control unit 121, as well as the control unit 111 and the control unit 121, are connected via a communication line, the control form of a so-called master-slave is adopted, in which each of the control units 102, 121 of the image reading device 1 and the image recording unit 3 executes the control upon a command from the control unit 111 in the image processing unit 2.

In addition to the control unit 111, the image processing unit 2 includes an interface (I/F) control unit 112 which is a general-purpose parallel interface control circuit such as an IEEE488 interface or a so-called GPIB interface, a multi-value synthesis unit 106 for carrying out a variety of processing of the image, an image processing device 107 as described below, a head correction unit 123 for correcting density unevenness, a digitizing processing unit 108 for carrying out digitizing processing of the image data, and a buffer memory 110 for storing the image data, and has a control unit 20 connected thereto. The control unit 111 operates upon a command from the operation unit 20 and the computer (not shown). The operation unit 20 provides the selection command regarding the assignment of the color or the editing when reading the original or the assignment of the operation. It also provides a command for the density unevenness correction when forming the image, as described below. This control unit 111 has a property of controlling via the interface (I/F) control unit 112, thus allowing the input or output of the image data from or to an external computer or the remote control with an external device via an interface connected to the interface (I/F) control unit 112. Further, the control unit 111 carries out the control over the multi-value synthesis unit 106, the image processing device 107, the head correction unit 123, the digitizing processing unit 108 and the buffer memory 110.

In addition to the control unit 102, the control system of the image reading device 1 includes a mechanism drive unit 105 for driving a mechanical portion of the image reading device 1, exposure control units 103, 104 for carrying out exposure control of a lamp (not shown) when the original is read, an analog signal processing unit 100 having a CCD 16 connected thereto to carry out a variety of processing of the image, and an input image processing unit 101.

The control unit 102 performs control over the mechanism drive unit 105, the exposure control units 103, 104, the analog signal processing unit 100, and the input image processing unit 101.

The control system for the image recording unit 3 includes, in addition to the control unit 121, a mechanism drive unit 122 for driving a mechanical section of the image recording unit 3, a head driver 116 for driving each of the recording heads 117 to 120 for each color, and a synchronization delay memory 115 for correcting a delay caused by the mechanical structure of the recording heads 117 to 120 by recording the time division of the operation of the mechanical section in the image recording unit 3. The synchronization delay memory 115 also includes a circuit for generating the timing necessary for driving the recording heads 117 to 120. The control unit 121 controls the synchronization delay memory 115 and the mechanism drive unit 122.

The image processing flow in this embodiment will be described below with reference to Fig. 7.

In the image reading device 1, an image formed on the CCD 16 of the CCD unit 18 (Fig. 5) is converted into an analog electric signal by the CCD 16. The converted analog electric signal (image information) is serially processed in the order of R (red), G (green) and B (blue) to be supplied to the analog signal processing unit 100. The analog signal processing unit 100 carries out sample-and-hold for each color R, G and B, correction of the black level and control of the dynamic range, and carries out analog/digital conversion (A/D conversion) into a serial multi-value digital image signal (8 bits long for each color in this embodiment) to be output to the input image processing unit 101. The input image processing unit 101 carries out the processing necessary for reading system, such as CCD correction and gamma correction, by directly acting on the serial multi-value digital image signal, the result being output to the image processing unit 2 as original image data.

In the image processing unit 2, the multi-value synthesis unit 106 carries out the selection and synthesis of the digital image signal (original data) of the serial multi-value signal sent from the image reading device 301 and the digital image signal sent from the external computer (not shown) through the parallel interface (I/F). The selected and synthesized image data is supplied to the image processing device 107 as a serial multi-value digital image signal. The image processing device 107 is a circuit for carrying out the smoothing processing, the edge processing, the black extraction and the mask processing for the color correction of the recording ink for use in the recording units 117 to 120. The serial multi-value digital image signal is caused to undergo the above-mentioned processings in the image processing device 107. And the output of the image processing device 107 is supplied to both the head correction unit 123 and the buffer memory 110. The output of the head correction unit 123 is supplied to the digitizing processing unit 108, although the head correction unit 123 will be described further below.

The digitizing processing unit 108 is a circuit for converting the serial multi-value digital image signal into a binary value, whereby either the simple digitization at a fixed slice level or the pseudo-halftone processing using the dither method is selectable. The serial multi-value digital image signal is converted into a binary parallel image signal of four values, which is output as image data to the image recording unit 3.

In the image recording unit 3, the binary parallel image signal (image data) from the image processing unit 2 is transferred to the synchronization delay memory 115, on the basis of which the head driver 116 drives each of the recording heads 117 to 120, which eject the inks of the colors cyan, magenta, yellow and black, respectively, so that the image is printed on the fabric.

The interface (I/F) with the external computer and the like is described below.

The multi-valued original image data read by the image reading device 1 is temporarily stored in the buffer memory 110. This image data is transmitted to the computer (not shown) through a parallel interface such as a GPIB while being synchronized by the I/F control unit 112. The image data transmitted to the computer is edited and color-converted using a CRT display device and stored as an image file on a floppy disk, a hard disk or an optical disk. It is a matter of course that the image data can be simply stored without specially processing it. Also, it will be clear that an image such as a computer graphic (CG) created directly on the computer without using the image reading device 1 can be treated in the same manner as the image read by the image reading device 1.

The image data of the image file thus created and stored is transferred to the buffer memory 110 via the parallel interface such as GPIB as described above, and then transferred from the buffer memory 110 to the head driver 116 via the multi-value image synthesis unit 106, the image processing device 107, the head correction unit 123, the digitizing processing unit 108, the synchronization delay memory 115, so that the image data is printed by the recording heads 117 to 120.

Referring to Fig. 8, the details of the head correction unit 123 will be described below.

Each nozzle of the recording heads 117 to 120 arranged in the image recording unit 1 is manufactured in the same manner, but the nozzle diameter may be slightly different, whereby the ink ejection direction of each nozzle may be slightly deviated due to the influence of the ink adhering to the vicinity of the nozzle or the ejection amount may be different. For this reason, even when image data is printed at a certain density, some unevenness may occur, which is expressed as stripes in the main scanning direction. In order to correct such unevenness to achieve the uniform printing at a certain density, the density of the image data corresponding to the nozzle portion having a lower density (or higher density) is increased (or decreased) according to the printing density so as to form a uniform printing density. The head correction unit 123 serves to carry out such correction. It is assumed here that each of the recording heads 117 to 120 is equipped with 256 nozzles.

In the head correction unit 123, the characteristic information of density unevenness for all 256 nozzles of the recording heads 117 to 120 corresponding to the colors C, M, Y and Bk (selection information for selecting which of a plurality of correction data written in a correction RAM 262, as described below, is used for correction) is written into a selection RAM 260 by the CPU 256. The selection RAM 260 is capable of storing the characteristic information corresponding to the number of nozzles or 1024 (= 256 × 4) nozzles. The image input data VDin is serial multi-value digital image data from the image processing device 107, which is 8 bits wide in this embodiment, and the color component image data (8 bits) per pixel is sequentially input for pixel points in the order of Y, M, C, Bk, Y, M, C, Bk and so on. From the selection RAM 260, the data is retrieved according to the order of the image data for input by incrementing the address in the sequence. There are also arranged a bidirectional buffer 263 for writing the selection data into the selection RAM 260, and further a selector 259 for selecting either the low order 10 bits of the address of a 16-bit address bus output from the CPU 258 and a 10-bit output of the counter 250. The counter 250 is such that a hold signal HS and a clock signal CLK are input from the outside, and the clock CLK is counted and output as 10-bit data. This 10-bit data or the data input as the address of the selection RAM 260 is used to select a specific nozzle from among the above-mentioned 1024 nozzles. As described above, the image input data VDin consists of color component image data per pixel to be input in the pixel sequence, and the output of 10 bits wide from the counter 250 can designate the pixels corresponding to the current image input data VDin by synchronizing the clock of the image input data VDin with the clock input to the counter 250. The selector 259 selects the output of the CPU 258 when the data is written into the select RAM 260 and the output of the counter 250 when the data is read from the select RAM 260. Note that a flip-flop 252 for temporarily storing the data is arranged on the output side of the select RAM 260.

The correction RAM 262 has a correction table which is written by the CPU 258 and is connected to the data bus of the CPU 258 via a bidirectional buffer 254. The correction table has data as shown by the solid lines or the dashed lines L1 to L5 in Fig. 9. Here, the correction table has five pieces of data as shown by the solid lines or the dashed lines L1 to L5, but in practice, larger pieces of correction data are included in the correction table. For example, if the output data from the selection RAM 260 is 8 bits long, 256 kinds of correction data can be stored. The selector 216 selects either the 16-bit address from the CPU or 16 bits of the summation of the 8-bit output from the flip-flop 252 and the 8-bit data of the input image data VDin for input to the correction RAM 262.

The correction data represented by the solid lines or the dashed lines L1 to L5 as described above are selected according to the input addresses for the correction RAM 262. That is, when the selector 261 selects the B side as shown, 8-bit data of the input image data VDin and the 8-bit data output from the select RAM 260 are input to the correction RAM 262 as the address A. Specifically, the 8-bit data output from the select RAM 260 is used to select one of the solid lines or the dashed lines L1 to L5 as described above. Note that, of these solid lines or dashed lines L1 to L5, the solid line is for the equal magnification and the dashed line is for the variable magnification. Because the range of nozzles for use in the recording heads 117 to 120 differs depending on the magnification, the correction data indicated by the solid line or the broken line according to the range of nozzles used in the recording heads 117 to 120 is written by the CPU into the correction RAM 262. Also, the correction table written into the correction RAM 262 is for outputting the correction data ΔA for the address input A, such correction data ΔA is once latched by the flip-flop 254, added to the input image data VDin by an adder 256, and output as correction data or output image data VDout through a flip-flop 257 for data latching.

That is, a correction table is stored for each pixel in the selection RAM 260, the value of the correction data corresponding to the input image data VDin is read from the correction RAM 262, and the read correction data is converted by the A flip-flop 255 is arranged to latch the input image data VDin to be input to the adder 256. While the correction data is represented by lines in Fig. 9, it will be appreciated that the correction data may be represented by curves rather than lines.

A method of generating the characteristic information regarding the density unevenness to be written into the selection RAM 260 is explained below.

When the correction of density unevenness is instructed from the operation unit 20 connected to the image processing unit 2, the generation of the identifying information is carried out in the order of C, M, Y and Bk. As shown in Fig. 10, first of all, a monochromatic stripe-shaped gradation pattern for each of the colors C, M, Y and Bk with an arbitrary density is generated by three lines each by a pattern generator (not shown) (one line in a width which can be recorded at one time by the ink jet head 9) and printed by the image recording unit 3. The pattern generating means is arranged in the multi-value synthesis unit 106 as shown in Fig. 7 to generate 8-bit data of the fixed value instead of the image data from the buffer memory 110 and the input image processing unit 101. The density data to be generated at this point is 50%, although it can be selected as 33%, 50% and 100%, for example. Of course, the head correction unit 123 is set to prohibit the correction so that the pure characteristics of the recording heads 117 to 120 are directly printed.

The density unevenness correction pattern thus output is input to the image reading device 1 to read the image reading area 4 for this correction pattern and to obtain the amount of density unevenness for each nozzle in the recording heads 117 to 120 and thereby to generate the identifying information. The above-described process is repeated for all the recording heads 117 to 120 in the order of C, M, Y and Bk to generate the identifying information, which is then written into the selection RAM 260. In this way, the setting of the density unevenness correction data in the head correction unit 123 is completed. Thereafter, when the current image is output, the correction of the density unevenness is carried out before the printing is carried out using this correction data at any time in real time.

The operation of the ink jet recording unit A-2 will be described below with reference to Fig. 3.

Upon receiving a recording start signal, the operation of the ink jet recording unit 1 is started. First, the print recovery operation is carried out with the ink jet head 9 capped. Then, a capping unit 24 of the head recovery device 13 is separated from the ink jet head 9, and the ink jet head 9 is moved from the home position to the start position. After a short wait at the start position, the ink jet head 9 and the ink supply device 11 move reciprocally along the guide rails 7, 8 in synchronization with an operation signal or image signal transmitted from the image processing unit 2 (hereinafter referred to as a main scan or simply as a main scan). By doing so, the ink is ejected according to an image signal from each of the recording heads 117 to 120 within the ink jet head 9 onto the cloth 36 held in facing position on the side, so that an image is formed on the cloth 36. When the ink jet head 9 moves reciprocally on the guide rails 7, 8 once, the cloth 36 is transported by the image width (ie, the width of the cloth 36 in a transport direction which can be printed by one scan of the ink jet head 9), and then the next main scanning is carried out. When the image recording after repeating the above-described operation is completed, the ink jet head 9 is moved to the home position and capped by the head recovery device 13.

By repeating the above-described operation over a specified length, the recording is carried out on the fabric 36 of the roll fabric. Although the length of a roll of fabric is limited, it is possible to continuously record by sewing the rear end of the roll of fabric 36 to the front end of the next roll of fabric at the time when the roll of fabric 36 is unwound from a winding core 33. For such a purpose, colored thread is used for sewing, and a density detection sensor 38 is arranged upstream of the platen roller 40, whereby, in the case where such a part is detected by the density detection sensor 38, the recording is temporarily stopped after one recording cycle (an operation of the ink jet head 9 in a main scanning direction) is completed when the sewn part is immediately transported in front of the ink jet head 9. Thereafter, the fabric 36 is further fed in predetermined amounts until the sewn portion reaches a position immediately downstream of the ink jet head 9 so that recording can be restarted. In this procedure, when the ink jet head 9 scans and records the sewn portion, which is generally thicker, the ink jet head 9 is prevented from sliding on the sewn portion, which may cause stains on the fabric or damage to the ink jet head 9.

The printed fabric 36 passes through a position opposite to the drying unit 46, whereby solvent and water contained in the ink are removed during the passage, so that it is possible to prevent the color of the image from changing due to the effect of the solvent or water content when the fabric is wound up.

Referring to Fig. 11, the operation of a control system for controlling the transport operation of the cloth 36 in the image recording unit 3 will be described below. Fig. 11 is a block diagram showing a circuit configuration of the ink jet recording unit A-2 and the cloth transport unit 43 in the image recording unit 3.

The control unit 160 is a control circuit for controlling a web transport unit 43. The control unit 160 and the control unit 121 of the ink jet recording unit A-2 are connected via the communication line.

The control unit 160 serves to drive a drive motor 163 via a motor driver 162, and the drive motor 162 serves to drive a conveyor belt 37 (Fig. 2). A conveyor system operation unit 161, which is connected to the control unit 160, serves to operate the tissue conveyor unit 43 from the outside, and the initialization for initiating recording and transportation after recording is carried out in response to a command from the conveyor system operation unit 161.

The stop switch 164 connected to the transport system operation unit 161 is a switch for use in temporarily stopping the printing operation, in which case a signal is transmitted from the control unit 160 to the control unit 121 when this switch is turned on. Upon detecting this signal, the control unit 121 stops the printing operation until the switch is turned off. The stop operation is performed when a recoverable abnormality such as ink absence or a sewn part with connected fabric parts is detected during printing. If there is no ink, the ink is replenished, or if the sewn part is detected, the fabric is conveyed until the sewn part is located immediately downstream of the ink jet head, in which case the printing operation is restarted by turning the stop switch 164 to the off state. Similarly, the emergency stop switch 165 connected to the Transport system operation unit 161 is connected to a switch which is used when the printing operation is to be stopped immediately, in which case when this switch is turned on, a signal is transmitted from the control unit 160 to the control unit 121. Upon detecting this signal, the control unit 121 immediately stops the scanning of the ink jet head 9 (Fig. 2) and terminates the printing operation. Instead of arranging the stop switch 164 and the emergency stop switch 165, an error detection signal indicating the abnormality such as the lack of ink may be directly transmitted to the control unit 121.

The conveyance of the web 36 during recording is carried out in accordance with a signal from the control unit 121 in the ink jet recording unit A-2. Fig. 12 shows a timing chart of communication for conveyance between the control unit 121 and the control unit 160. The web conveyance command signal is a signal transmitted from the control unit 121 on the ink jet recording unit 1 to the control unit 160 on the web conveyance unit 43, being LOW in the normal operation and becoming HIGH upon completion of a line of printing by the ink jet head 9. The control unit 160 of the web conveyance unit 43 drives the conveyance motor 63 to start conveyance of the web 300 when the web conveyance command signal becomes HIGH. The tissue transport stop signal is a signal transmitted from the control unit 160 of the tissue transport unit 43 to the control unit 121 of the ink-jet recording unit 1, being LOW in the normal operation and becoming HIGH during the transport of the tissue. Upon detecting the tissue transport stop signal at HIGH level, the control unit 121 of the ink-jet recording unit 1 determines that the tissue transport command signal has been accepted and turns the tissue transport command signal to LOW.

If the tissue transport stop signal does not go HIGH even if a certain time has passed after the tissue transport command signal goes HIGH, or when the cloth transport stop signal, which is once turned HIGH, does not become LOW even after a certain time has passed, the control unit 121 of the image recording unit 3 judges that an abnormality has occurred in the cloth transport unit 43 to interrupt the recording operation and indicate the abnormality in the operation unit 20 connected to the image processing unit 2. In this way, by exchanging the cloth transport command signal and the cloth transport stop signal, the recording/printing with the ink jet head 9 and the transport of the cloth 36 can be selectively carried out.

As described above, in this embodiment, an image signal of the original image read by the image reader 1 is processed in the image processing unit 2, and ink jet recording is performed on the cloth 36 in the image recording unit 3 based on a processing result of the image processing unit 2 to perform the cloth printing.

As described above, according to the present invention, the image is formed directly on the fabric using ink jet recording without the need for a screen printing plate required in conventional textile printing, so that the processes and time required for printing on the fabric can be reduced significantly and the apparatus can be made smaller. Of course, the image information for printing can be stored on a medium such as a tape, a floppy disk and an optical disk, with excellent storage capacity and long-term preservation of the image information. Furthermore, the processing of the original image such as color change, layout change and enlargement or reduction can be carried out in a short time.

The inkjet textile printing apparatus of the present invention has a higher efficiency in terms of system construction. For example, the image reading device for reading the original image to the image processing unit for conversion into an image signal. Also, in this invention, by enabling the connection between the image processing unit and the external computer for exchanging the image data, a plurality of images can be recorded on the tissue.

In the ink jet textile printing apparatus of the present invention, the image recording unit for performing recording on the fabric may comprise, in addition to an ink jet recording unit, a fabric feeding unit for feeding the fabric to a position corresponding to the ink jet recording unit, a fabric transporting unit for transporting the fabric to the ink jet recording unit exactly on a side opposite to the ink jet recording unit, and a post-processing unit for post-processing the printed fabric. In this case, in order to facilitate maintenance, it is desirable that the ink jet recording unit be arranged opposite to and spaced from the fabric transporting unit. Further, in order to cope with the discharge of the ink or the sewn part between the cloth sheets, it is preferable to further provide the ink jet textile printing apparatus of the present invention with a control means for stopping the image recording on the cloth and for restarting the image recording according to the image data immediately before the stopped image data when the stop is released.

The ink jet recording unit for use in the ink jet textile printing apparatus is not specifically limited as long as it carries out recording by ejecting fine ink droplets, but more excellent effects can be achieved by having electro-heat conversion means for generating heat energy for ink ejection. In this case, the ink jet recording unit may be constructed to eject the ink by utilizing film boiling caused by the electro-heat conversion means. directions, through ejection nozzles onto the tissue.

The effects of the present invention are as follows:

(1) Because there is no need for the textile printing plate such as a silk screen plate, 1. the processes and time for recording the original image can be reduced significantly, 2. mixing a number of color inks according to the image becomes unnecessary, 3. small-batch production becomes possible, 4. preservation of the recording information is easy, 5. only a small device and small installation space are required, and 6. editing of the original image such as layout change, color change and enlargement or reduction can be easily carried out. (2) Due to the application of the ink-jet recording method, the image representation is improved: 1. high resolution, 2. excellent color reproduction.

(Second embodiment)

The basic structure of an ink jet recording apparatus is the same as that shown in Fig. 2 of the first embodiment, and the explanation is omitted.

Referring to Fig. 2 and Fig. 13, which is a perspective view showing the essence of a recording unit, this embodiment will be described below.

In Fig. 13, the web 36 of the recording medium is adhered to a belt 37 and is fed stepwise in an upward direction as shown. In a first printing unit 31 located at the bottom of the figure, a first carriage 44 is provided with the arranged ink jet heads of the specific colors S1 to S4, as well as Y, M, C and Bk. The ink jet head (recording head) in this embodiment has elements for generating the heat energy, which causes film boiling in the ink, rather than the heat energy used to eject the ink, and has 128 ejection orifices arranged at a density of 400 dpi (dots per inch).

Downstream of the first printing unit, there is arranged a drying unit 45 which has a heating plate 34 for heating from the back of the belt and a hot air duct 35 for drying from the front. The heat transfer surface of the heating plate 34 is arranged in contact with an endless belt 37 which is highly tensioned to transfer the heat from the back of the conveyor belt 37 due to the high temperature and high pressure steam passing through a hollow interior. The fabric 36 on the conveyor belt 37 is effectively heated by the heat transfer. On the inner surface of the heating plate, heat collecting flat elements 34' are arranged to effectively absorb the heat on the back of the belt. The sides which are not in contact with the belt are covered with heat insulating material 43 to prevent the occurrence of damage due to heat radiation.

On the front side, the drying effect on the fabric is further increased by applying the low humidity air to the fabric to be dried which has been exposed to the hot drying air blowing from a supply duct 30 on the downstream side. And the air having sufficient humidity and flowing in the opposite direction to a transport direction of the fabric is sucked out in a larger amount than a blowing amount from a suction duct 33 on the upstream side, so that the evaporated water portion is prevented from covering the surrounding mechanical components with dew. A hot air supply source is arranged on the back side, and the suction effect is carried out on the front side, so that the pressure difference between the blow-out opening 38 and a suction opening 39 arranged opposite the fabric is uniform over an entire area in a longitudinal direction. The The air blowing/suction unit is offset downstream from a center of the heating plate arranged on the rear side so that the air can be blown to the sufficiently heated portion. Thereby, it is possible to intensively dry a quantity of water contained in the ink containing the reducing agent which the first printing unit 31 has applied to the cloth.

On the outlet side (upper side) a second printing unit 31' is arranged, which has a second carriage 44' with the same structure as the first carriage.

The side on which the reducing head was arranged is used for the special color (e.g. gold ink with finely divided gold grains), e.g. as a side for the reserve head (S). Also, a post-processing head P' which has no action except immediately after the recording is arranged in a final position as shown. This second recording unit is for recording dark and sharp patterns which are overlapped mainly for control.

As shown in Fig. 13, the cloth 36 of the recording medium is adhered to a belt 37 to be fed stepwise in an upward direction. The first recording unit 31 on the lower side is equipped with a first carriage 44 which has arranged ink jet heads {a total of 8 heads for a head for special processing which is carried out immediately before recording depending on the material of the cloth or the type of pretreatment: P, Black: Bk, Reducing agent (pre-jetted to spread the ink jetted later): D, Magenta: M1, Special color of magenta type: M2, Cyan: C1, Special color of cyan type: C2, Yellow: Y (M, C, Y is in the order of causing more bleeding)} in this order. The first recording unit mainly records bright image portions in a recording process (indicated by the solid line arrow) using a reducing agent (clear ink which does not contain any dye) Clear ink recording is carried out in such a manner that for a discrete color dot, clear ink is applied, with less clear ink in higher density, four to nine dots in adjacent positions around a dot of color ink with that pixel position to cover the dot of color ink, with less roughness in the light portions, and without excessive wetting of the fabric.

The printed fabric is peeled off, dried again in a drying unit 46 having a heating plate and a hot air duct, guided along a guide roller 41 and wound up on a winding roll 39. The wound up fabric is taken out of the main facility in a batch process, dyed, cleaned and dried to provide products.

Referring to Fig. 14, an overlay recording method will be described below.

As explained above, eight heads are integrally formed in each recording unit, but in this figure, each head column in the recording unit is represented by only one head for simplification.

In this embodiment, serial recording is first carried out by the first recording unit 31 arranged on the upstream side at a quarter of the predetermined final recording density (ejection amount per unit area), then feeding of the cloth is carried out in a distance of half the recording width w, and serial recording is further carried out at a quarter of the final density. Thus, the overlap area is printed at a half of the final recording density. By repeating this operation, the image is printed at a half of the final recording density in the first recording unit. Then, the cloth is dried sequentially as described above while passing through the drying unit 45. Then, the The second recording unit 31, which is arranged on the output side, carries out the overlapping recording as in the first recording unit. In summary, this means: a quarter of the density x four times the overlap = 1, ie the recording is achieved with a predetermined recording density.

It is noteworthy that, due to the arrangement of the drying unit 45 between the first and second recording units, recording can be achieved at a "predetermined recording density" which is substantially equal to twice the conventional density (slightly different due to the use of thinner ink) or at a sufficient density.

The positional relationship between the coincidence in the scanning in the first recording unit 31 and the coincidence in the second recording unit 31 is as follows: Although the coincidence occurs at half the recording head pitch in both the first recording unit and the second recording unit, the coincidence of the second recording part is directly halfway between the coincidence positions of the first recording, so that the coincidence positions cannot overlap in this embodiment. The distance d between the first recording unit and the second recording unit and the head width w have a relationship:

d = (n + 1/4)w n: natural number.

Here a notable problem of the collision stripes between the samples occurs.

When serial scanning to perform recording at 100% density at a time, white stripes may appear at 0% density or dark stripes at 200% density, but not at 100% density, due to gaps or overlaps caused by various errors in connection with the feed amount of the fabric or by ink stains which produce image defects.

However, according to this embodiment of the present invention, the recording is only achieved with a quarter = 25% with one scan and covered three times at the proper density (not at the coincidence position), so that the recording can be achieved at 100% density or, at worst, slightly thinner at 75% density or slightly denser at 125% density. And the width of this stripe is made approximately half because the error amount is divided in half. With these two effects, no coincidence stripes are apparently observed.

Also, certain random deviations or streaks caused by false discharge are covered by other normal triple coverage recordings.

That is, since a pixel position is swept four times by the same color head according to this embodiment, that pixel position can be covered with the same color up to four dots at most. And the operation of overlay recording for two dots, drying and next overlay recording results in less bleeding. That is, the multi-value representation is permitted in which the dot number has five values (gradations) of 0, 1, 2, 3, 4, rather than the binary representation of hit or miss with the normal ink jet. Since five color heads except black are provided in this embodiment, color representation in five gradations to the fifth power, i.e., 5⁵ = 3125 colors per pixel, is enabled. This calculation assumes that 4 dots × 5 colors = 20 dots per pixel are possible. However, the actual number of colors may be less than 3125 colors because the drying process allows only 10 to 16 dots to hit a pixel without bleeding. However, with an error The entire gradation reproduction is possible due to the division process, and also due to the effects of the reducing agent.

Another recording unit/drying unit (pre-recording unit/pre-drying unit) can be arranged upstream of the first recording unit in the above-described embodiment. This pre-recording unit applies a pre-treating agent for dyeing the fabric according to the recording pattern instead of the ink. Different types of the treating agent are supplied to the heads of the pre-recording unit to suit a variety of fabric materials. After the pre-treating agent is solidified in the pre-drying unit, recording is carried out on the side treated with the treating agent in the first and second recording units downstream, as in the above-described embodiment. This prevents the loss of the treating agent and the use of detergent in post-processing can be reduced. Although inkjet textile printing is inherently environmentally friendly and does not use a dye mixture that is almost washed out, other effects are to be expected.

This pre-recording unit does not require high resolution. It has half the resolution of the first/second recording unit, and is rather designed to have no false discharge and higher resistance to treatment agents.

Another recording unit (post-recording unit) may also be provided to increase the effects of post-processing.

The recording method in the first/second recording unit is not necessarily limited to the one recording method described above (the manner of overlap or number, meeting positions, etc.). It is an object of the present invention that a recording width is supplied in multiple steps. the drying process is at least provided to carry out the overlap recording and the meeting positions in the first and second recording units never coincide, with possible variants such as a (two recording units for the triple overlap recording/one drying unit and b) three recording units for the double overlap recording/two drying units.

The above-mentioned method of a) can reduce the unevenness and streaks. The method of b) can achieve a higher density.

Another method is also possible in which the feed pitch is just one scanning width and the relative position in the first/second recording unit is shifted by w/2. In this case, the higher recording speed is achieved with a lower number of overlap recordings, although the ability to cover the unevenness and stripes may be reduced.

As described above, according to the present invention, the fine gradation or added value can be realized at the increased maximum density, wherein the image can be formed with less bleeding, unevenness, streaks or roughness.

(Third embodiment)

The third embodiment of the present invention will be described in detail below with reference to the drawings.

Fig. 15 shows a cross-sectional view of a recording apparatus according to the invention. Reference numeral 301 denotes a recording apparatus main body, 302 denotes a long roll of a recording medium, 304 denotes a cutter for cutting the recording medium to a predetermined length, 303, 305 denote a pair of transport rollers for transporting the recording medium in a transport direction, and 306 denotes a sub-scan roller for accurately transporting and positioning the recording medium to an extent corresponding to a print width of the recording head, as described below. With the above-described structure, the transport path of the recording medium to be fed from the roller 302 is formed.

Numeral 309 denotes a carriage for carrying a recording head as described below so as to be movable in a vertical direction with respect to the drawing (a horizontal direction in the actual recording apparatus) by means of a pair of main scanning rails 309a. 310 denotes a printing plate which is arranged in opposition to the carriage 309 with the recording medium therebetween, and further comprises suction adsorption means such as an air suction adhesive plate or an electrostatic adhesive plate for preventing the recording medium from coming into contact with the recording head as well as preventing the floating of the recording medium held on the plane during printing.

As shown in Fig. 16, the environment of the recording head is described below. The carriage 309 has the recording heads 309C, 309M, 309Y, 309Bk corresponding to cyan, magenta, yellow and black. 311 denotes an ink supply system for supplying the ink to the recording heads 309C, 309M, 309Y, 309Bk which have ink cartridges 311C, 311M, 311Y, 311Bk corresponding to cyan, magenta, yellow and black. The ink is supplied to the recording heads 309C, 309M, 309Y, 309Bk by a pump not shown via tubes 312C, 312M, 312Y, 312Bk. Reference numeral 313 denotes a motor for scanning and driving the carriage 309 in the main scanning direction (left and right in the figure), the carriage 309 being driven via a pulley 314 which is fixedly connected to the motor 313. a pulley 315 and a belt 316, 317 denotes a motor for scanning and driving the ink supply system 311 in the main scanning direction (left and right in the figure) in synchronism with the carriage 309, the ink supply system 311 being driven via a pulley fixedly connected to the motor 317, a pulley 319 and a belt 320.

322 denotes a roll of the first recording medium as described above, which is transported upward as shown by the transport roller 305 and the sub-scan roller 306. 323 denotes a cap member which is arranged in a position to carry out a process for removing the factors deteriorating the image quality (hereinafter referred to as "ejection recovery processing"). With the nozzle surface of the recording heads 309C, 309M, 309Y, 309Bk covered by the cap member 323, the ink is ejected by driving the recording heads or by applying pressure through the recording head nozzles. Furthermore, within the cap member 323, a high-speed air flow is directed to the recording head nozzle surfaces to blow off residual inks, dirt and lint associated with ink ejection from the nozzle surfaces, thereby cleaning the nozzle surfaces to eliminate the mis-discharge and the unevenness.

Reference numeral 331 denotes a monitoring device for monitoring the recording state of the recording head or a predetermined test pattern 332 (uniform density pattern) of the test image recorded at a predetermined time interval on a second recording medium 341, which is provided for the monitoring device arranged at one end of the plate 310.

The monitoring device recording medium 341 as described above is fed by the feed roller 342 in synchronism with the printing of the predetermined pattern 332 on the printing plate 310, and after printing, it is wound up on a winding roll 343 by the monitor 331. The monitor recording medium 341 uses a recording paper for ink jet printing. An example of the recording paper for ink jet printing includes a paper in which an aqueous polyvinyl solution with silicic anhydride powder or alumina powder mixed therein is coated on the surface of the paper and then dried (see, for example, Japanese Patent Document No. 2-43083). A recording paper thus treated is less likely to bleed ink than the normal untreated recording paper and is suitable as the second recording medium for the monitor in this invention.

The pitch (recording pitch) of the above-mentioned predetermined pattern is based on the completion of recording of a unit pattern or the length in a sub-scanning direction (a transport direction of the recording medium) corresponding to the unit pattern, because in the case where textile printing is carried out, for example, the recording is often repetitive of the unit pattern, there is a possibility of reducing the occurrence of errors in textile printing due to mis-ejection. The recording of the above-mentioned predetermined pattern may be carried out whenever the recording for a predetermined number of lines is completed. In this case, the above-mentioned predetermined number of lines is appropriately determined depending on the probability of mis-ejection of the recording head and the surface state of the fabric. Even if calibration is performed for each line, the detection of abnormality is possible in real time, while in the case of it being performed for all predetermined lines, the recording speed will not decrease during recording.

It should be noted that the distance of the predetermined pattern 332 can be increased or decreased if necessary because there is some difference in the probability of ink mis-ejection depending on the type of textile printing ink. It is assumed that the predetermined pattern 332 is a fixed pattern in which the recording frequency is set to, for example, 50% of the normal frequency.

Referring to Fig. 17, the monitor 331 will be described in detail below. In the same figure, reference numeral 332 denotes a calibration pattern recorded on the monitor recording medium at a predetermined pitch, printed for scanning in each color of cyan, magenta, yellow and black, and with uniform density. Reference numeral 333 denotes a pair of illumination lamps for illuminating the calibration pattern 332. 334 denotes a projection lens for projecting the calibration pattern 332 illuminated by the illumination lamps, and 335 denotes a sensor such as a CCD for carrying out the photoelectric conversion of the calibration pattern 332 projected by the projection lens 334. The number of elements is desirably larger than the number of recording elements in the recording head. Based on the output of the sensor 335, the mis-ejection of the recording head or the printing unevenness beyond a predetermined degree is detected, and if necessary, the above-described ejection recovery process is carried out.

Referring to Fig. 15 and Fig. 16, a normal recording sequence will be described below. When a recording medium being fed from the roll 302 as shown in Fig. 15 is detected by a recording medium detection sensor (not shown) arranged immediately before the transport roller 305, the transport roller 305 and the sub-scan roller 306 are driven in the transport path by a predetermined amount, that is, until the leading end of the recording medium reaches the sub-scan roller 306.

When the leading end of the recording medium 332 is transported to the sub-scanning roller 306 as shown in Fig. 16, the carriage 309 and the ink supply system 311 are driven in a scanning direction (rightward in the figure) by the motors 313, 317, respectively. Likewise, the recording heads 309C, 309M, 309Y, 309Bk perform recording in a print width as indicated by reference numeral 301 in the figure based on the image signal.

After line printing, the carriage 309 and the ink supply system 311 are returned to the predetermined positions on the left in the figure, and the recording medium 322 is transported by a motor 321 exactly in the printing width 301.

After the above-explained printing sequence and the transport of the recording medium are repeated in predetermined cycles, the recording medium 322 is discharged from the apparatus.

Next, the motor 331 will be described. Fig. 18 shows an output signal of the sensor 335 in the monitor 331. The abscissa axis corresponds to each pixel of the sensor 335, and the ordinate axis represents the output corresponding to each pixel. The output of the sensor 335 is corrected as a white level or subjected to so-called shadow correction with the recording medium before pattern printing. The output of each pixel corresponds to each nozzle of the recording head, whereby the measurement of the ejection amount of each nozzle is possible.

If there is at least one output overshoot value b which is larger than the average value a by a predetermined value against the pixel outputs, mis-ejection is judged. Also, if there is at least one output overshoot value c which is larger or smaller than a predetermined value than a value d which is smaller than the average value a by a predetermined value, unevenness is judged.

Empirically, the "slice level" b for misejection detection is a value over 50%, which is larger than the mean value a, and the "slice level" c, d for non-uniformity detection is desirably about 5% to 10% larger or smaller than the mean value a.

The judgment of unevenness is not limited to the method described above, but for example is a method based on whether the "slice level" is greater or less than the standard deviation over each pixel output of the sensor or the sum of the absolute values of the difference between adjacent pixels, i.e., A = Σai - ai + 1 , where each pixel output of the sensor is ai.

The value for unevenness correction corresponding to each nozzle of the recording head may directly be an output value of each pixel of the sensor 335 as described above, but the average value over adjacent pixels, e.g., three pixels before and after, of each pixel output from the sensor may be a pixel output to reduce the effects of noise.

It should be noted that the calibration sequence of detecting the mis-ejection and unevenness and the ejection recovery process are carried out under the control of the control unit (not shown) for controlling the entire recording apparatus. This control unit is equipped with a CPU such as a microprocessor, a ROM for storing the control programs and various data, and a RAM for use as the work area of the CPU.

Fig. 19 shows a flow chart of a calibration sequence of the detection of mis-discharge and unevenness and the discharge recovery process, which are executed by the CPU. The control programs for executing these processes are stored in the ROM.

First, in a printing sequence as described above, a calibration pattern is printed at a predetermined interval (step S1). The calibration pattern is read by the motor 31 (step S2), and the misdischarge is judged by the algorithm described above (step S3).

When the mis-discharge is judged, the judgement is made to execute the recovery process (step S4). The judgement in step S4 is made in view of whether or not the recovery process has already been executed in this sequence. This is based on an empirical fact that in the case where the discharge recovery process is properly executed, almost all discharge phenomena can be eliminated. After the recovery process is executed (step S5), the process returns to step S1, and then the printing of the calibration pattern is executed (step S1), the reading of the pattern (step S2) and the judgement of the mis-discharge (step S3). When the mis-discharge is judged again in step S4, a warning is displayed as a head trouble without the recovery process and the operation of the apparatus is stopped (step S6).

On the other hand, if the mis-ejection is not judged in step S3, the unevenness is judged based on an unevenness determination algorithm described above (step S7). If the unevenness is not judged, printing is continued (step S12). If the unevenness is judged to be equal to or larger than a predetermined value in step S7, the execution of the unevenness correction process is judged (step S8), and if necessary, the unevenness correction process is executed (step S9). The unevenness correction process in step S9 is to correct a drive signal (signal width or signal voltage) of the corresponding recording head based on an output signal of the pattern read in step S2. The same pattern is evenly density as that printed in step S1 is printed based on the drive signal after the correction (step S10) and read by the monitor 331 (step S11).

A sequence of these steps S7, S8, S9, S10, S11 is repeated a predetermined number of times (three times in this embodiment), and if the unevenness still exists, a warning is displayed as a recording head trouble and the operation of the apparatus is stopped (step S6). This is based on an empirical fact that in the case where more unevenness correction sequences are carried out, greater effects of the unevenness correction can be expected, but by repeating three times, sufficient effects can be obtained in the practical application state, while in the case where the unevenness is still noticeable after such unevenness correction processes are carried out three times, it is considered that there is a trouble of the recording head such as expiration of the life of the recording head in most cases.

When this series of calibration sequence is also carried out for each color of cyan, magenta, yellow and black, it is possible to maintain the ejection state of each recording head in an excellent manner without intervention. Accordingly, it is possible to increase the availability of the apparatus even by driving without an operator, which is particularly effective for recording on a long recording medium such as cloth.

Although the above-described embodiment is based on the use of cloth as the first recording medium, but is not limited thereto, there is also applicability to a recording medium which is susceptible to the ejection unevenness of the recording head, such as stained paper or a recording medium having patterns previously arranged on the surface. Examples of the cloth in this Invention includes fabrics, such as woven fabrics or nonwoven fabrics, made from cotton or silk.

As described above, according to the present invention, because the unevenness of the recording head is pronounced or the ink is more liable to bleed due to the texture of the fibers on the cloth or regenerated papers, a test image is recorded on the recording medium for monitoring and read by the monitoring means to judge an ejection state of the recording head even when the recording is carried out on the recording medium with inconspicuous mis-ejection of the ink from the recording head, whereby the accurate detection of the ejection state is possible regardless of the type or property of the recording medium, and the unevenness correction and the ejection recovery process are appropriately possible so that the recording can be carried out under the best ejection conditions at all times.

Furthermore, since the operation can be stopped when the non-recoverable state is judged, it is possible to suppress the occurrence of erroneous recordings to the minimum even when controlled without an operator.

(Fourth embodiment)

Fig. 20 shows a schematic view of an inkjet printer according to this embodiment.

In Fig. 20, reference numeral 401 denotes a main control unit for controlling the entire ink jet printer. This main control unit 401 comprises a CPU 511 such as a microprocessor, a ROM 512 for storing the control programs of the CPU or various data, and a RAM 513 for use as a work area and as a temporary storage for various data. Reference numeral 402 denotes a motor control unit for controlling rotation of a carriage motor 411 and motors 415, 416 for moving the sensors according to a command from the main control unit.

Each of the reference numerals 403 to 410 denotes a multi-nozzle ink-jet head (hereinafter referred to simply as an ink-jet head) for ejecting the respective color ink, the ink-jet heads 403 to 406 being arranged upstream of the recording medium 414 (recording paper, cloth) in a transport direction, and the ink-jet heads 407 to 410 being arranged downstream therefrom. The reference numerals 403, 404, 405 and 406 are respectively ink-jet heads for cyan, magenta, yellow and black. Also 407, 408, 409 and 410 are respectively ink-jet heads for cyan, magenta, yellow and black.

Reference numeral 411 denotes a carriage motor for scanning a carriage with the ink jet heads arranged thereon. 412 denotes a motor for moving a sensor 415, and 413 denotes a motor for moving a sensor 416. 415 is the sensor for reading the image recorded on the recording medium 414 while moving parallel to the moving direction of the ink jet head, and 416 denotes the sensor for reading the recorded image while moving parallel to the arrangement direction of the nozzles for the ink jet head (moving direction of the recording medium 414). 417 denotes an A/D conversion device for inputting a signal from each sensor 415, 416 and converting it into a digital signal for output to the main control unit 1.

Fig. 21 and Fig. 22 are block diagrams showing a structure of the main control unit in the inkjet printer according to this embodiment.

In Fig. 21 and Fig. 22, 421 denotes a calculation unit for calculating an adjustment amount for the alignment adjustment based on the value read from the sensors 415, 416. 422 denotes a frame memory for storing the image data. 423 denotes a palette conversion unit for separating the image data of each color. 424 denotes a gamma conversion unit for carrying out the recording correction. 425 denotes a head shading unit. 426 denotes a digitizing unit for converting the multi-value data for recording into binary data. 427 denotes an SMS unit for separating the recording data into those for the upper and lower ink jet heads. 428 denotes a memory for storing the binary data to be recorded, and 429 denotes a head control unit for controlling the recording with each ink jet head by supplying the recording data for the ink jet head.

The image data output from the frame memory 422 is separated for each color by the palette conversion unit 423, and the image data of each color undergoes gamma conversion and head shading. Further, it is converted into binary data by the digitizer unit 426, separated for each head by the SMS unit 427, and stored in the memory 428. The recording data stored in the memory 428 is read from the memory 428 by the head control unit 429 and supplied to each ink jet head for recording. Note that the recording data stored in the memory 428 is recorded for a plurality of recording tapes.

Fig. 23 is a view for explaining the state of the recording data stored in the memory 428. In Fig. 23, n denotes the number of nozzles in each ink jet head, and No denotes the number of recording lines per band. Reference numerals 436 to 439 each denote a memory area for storing the respective band data.

With this structure, the alignment of each ink jet head in the longitudinal direction can be carried out by designating the reading position of the recording data in the memory array shown in Fig. 23 when reading from the memory 428. For example, as shown in Fig. 23, when the reading start is (n-1, 0), the next recording data is image data in the second band. Here, when the position of the ink jet head beam head deviates by one pixel in the longitudinal direction, the positional deviation in the longitudinal direction is eliminated to record the image by setting its reading position to (n, 0). Fig. 24 is a block diagram showing a schematic structure of a memory reading circuit incorporated in the head control unit 429.

In Fig. 24, reference numeral 431 denotes a nozzle number counter for counting the number of nozzles for each ink jet head. Reference numeral 432 denotes an upper address counter, and 433 denotes a sub-address counter, the upper address counter 432 and the sub-address counter 433 permit access to each band memory in the memory 428. Reference numeral 434 denotes a reading start position setting register, an address set in this register 434 is set in the sub-address counter 433 to determine a lower reading address. Reference numeral 435 denotes a memory selection signal generating circuit for outputting a signal indicating which of the band memories 436 to 439 is to be read. 436 to 439 denote a band area in the memory 428. 436, 437, 438 and 439 denote storage areas for storing image data of the first, second, third and fourth bands, respectively.

In the above-described construction, the reading start position is first set in the register 434. The value to be set in this register 434 is a value corresponding to a deviation related to the positional deviation of the upper and lower ink jet heads, the deviation being obtained by a method described later. The start signal is a timing signal indicating the start of reading of each band, with the start signal setting the content of the register 434 on the sub-address counter 433 and starting reading of the recording data from each memory based on the sub-address. Assuming that the nozzle number of each ink jet head is 256, the 8 bits of the sub-address counter 433 are output as the sub-address.

On the other hand, the upper address counter 432 is incremented by +1 every time the nozzle counter 431 counts "256", the output of this upper address counter 432 being an address in the X-axis direction in a memory map as shown in Fig. 23. And the sub-address output from the sub-address counter 433 indicates a read address in the Y-axis direction (longitudinal direction) as shown in Fig. 23, in the case where the number of nozzles (n = 256) in the ink jet head is counted, the memory selection signal circuit 435 is activated to select the next band memory area.

In this way, by changing the value to be set in register 434, the alignment in the longitudinal direction can be carried out.

An automatic judgment method for the adjustment value for longitudinal alignment is described below.

Fig. 25A and Fig. 25B show views of examples of recording the patterns for alignment in the longitudinal direction.

In Fig. 25A and Fig. 25B, reference numeral 403 denotes a lower cyan head, and 407 denotes an upper cyan head. Although the ink jet heads for cyan 403, 407 are described here, it should be understood that the ink jet heads for other colors can be realized in the same manner.

In Fig. 25A, a distance of the recording width of one head (corresponding to n nozzles) is provided between the ink jet heads 403, 407, and in Fig. 25B, a distance equal to half the recording width of one head is formed between the upper ink jet head 403 and the lower ink jet head 407. In Fig. 25A, the recording is first carried out only by the first nozzle (upper nozzle) of the lower ink jet head 403 to record the line indicated by reference numeral 451. Then, the recording is drawing medium 414 is transported in a predetermined amount, and recording is carried out only by the first nozzle (upper nozzle) of the upper ink jet head 407 to record the line 452.

In Fig. 25B, recording is first performed only by the first nozzle of the lower ink jet head 403 to record the line 453. Thereafter, the recording medium 414 is transported in a predetermined amount, and recording is performed only by a middle nozzle of the upper ink jet head to record the line 454. This nozzle is the n/2-th nozzle when the number of nozzles in each ink jet head is n. In this way, by recording each line using the upper ink jet head 403 and the lower ink jet head 407, each line recorded by each ink jet head is overlapped when the alignment of these ink jet heads 403, 407 is accurately performed.

In this way, the image recorded on the recording medium 414 is read by the sensor 416 (Fig. 20), and the data thus read is an analog signal from the sensor 416 indicative of the brightness component of the image. This analog signal is converted into a digital signal by an A/D converter 417, and the value of each signal corresponding to each of RGB is obtained as an 8-bit signal (0H to FFH: H denotes hexadecimal).

For example, when the above-mentioned line is recorded in cyan, the monochromatic spectral characteristic is (R, G, B) = (0, FF, FF), the point being designated by reference numeral 463 when the position of a point 461 recorded by the ink-jet head 403 and the position of a point 462 recorded by the ink-jet head 407 coincide, as shown in Figs. 27 to 29. In this case, data from the sensor 416 is obtained as shown in Figs. 27-29 when m designates the recording position, Figs. 27, Fig. 28 and Fig. 29 respectively the R component, the G component and the B component.

Even if the upper ink jet head 407 deviates upward by one pixel with respect to the lower ink jet head 403 as shown in Fig. 30, the two recorded dots 461, 462 do not overlap as indicated by the reference numerals 461, 462. And the data from the sensor 416 reading these dots 464, 465 are shown in Figs. 31-33. The sensor 416 reads in a matrix direction of the nozzles as described above, and when the dot position deviates as shown in Fig. 30, its deviation appears as two peaks in Figs. 32 and 33.

As also shown in Fig. 34, when the ink jet head 407 deviates downward by one pixel with respect to the ink jet head 403, data as shown in Figs. 35-37 are obtained. In the graphs of Figs. 27-37, the spectral characteristic is (FF, 0, FF) when the color of the recorded line is magenta and (FF, FF, 0) when the color is yellow, so that in magenta, the G signal is regarded as the R signal of cyan, and the R signal is equivalently replaced by the G signal of cyan, while in yellow, the B signal is equivalently replaced by the R signal of cyan, and the R signal is equivalently replaced by the B signal of cyan. In black, the same output as the G signal or the B signal appears as the R signal of cyan.

With the result described above, the pattern of each color is read based on the lower ink jet heads 403 to 406, and in the case where the recording position of the upper ink jet heads 407 to 410 deviates upward, the reading start position from the memory is incremented by +1 when recording by the upper ink jet heads, while in the case where the recording position deviates downward, the start position is decremented.

In the manner described above, the amount of alignment of the recording position with the ink jet heads in a longitudinal direction is obtained, and the reading position from the memory is changed based on this amount, whereby the fine adjustment of the recording position can be carried out in a pixel unit without the need for an operator.

It is to be noted that the alignment of the recording position with each ink jet head in the moving direction of the carriage is carried out in such a manner that, as described in the conventional example, a grid pattern is recorded on the recording medium and the recorded image is read by the sensor 415 to obtain a deviation, and the reading position is changed by the memory 428 according to the deviation, so that the recording position is easily adjustable.

Fig. 38 shows a flow chart of processing for determining the deviation for alignment adjustment as described above, the control program for executing this processing being stored in the ROM 512 of the main control unit.

First, in step S1, scanning of the lower ink jet head is initiated, and in step S2, data for recording is output, e.g., with a special nozzle of the ink jet head 403 for cyan, to print a line, such as indicated by reference numeral 451 in Fig. 25A. Then, in step S4, the recording medium 414 is transported twice the length of the recording width of the ink jet head in the case of Fig. 25A. In steps S5 to S7, the line 452 is recorded this time by the upper ink jet head (head 7 in this case).

The recording medium printed in this way is then moved to a reading position with the sensor 416 trans ported (step S8), in which position the lines 451 and 452 are read by the sensor 416. Thereafter, in step S9, based on a reading result of the sensor, the deviation between the upper inkjet head and the lower inkjet head is determined. At this point, when the reading result as shown in Fig. 29 and Fig. 30 is obtained, for example, no positional deviation between the upper inkjet head and the lower inkjet head is judged, but when there is a deviation as shown in Fig. 32 and Fig. 33, a setting value for incrementing the reading start position is determined when recording with the upper inkjet heads 407 to 410. Also in the case as shown in Fig. 36 and Fig. 37, a setting value for decrementing the reading start position is determined when recording with the upper inkjet heads 407 to 410 (step S10).

In the first embodiment, as described above, when the alignment adjustment between the upper and lower ink jet heads for each color is carried out in a longitudinal direction, referring to the lower ink jet head for each color, it will be understood that one of the lower ink jet heads can be referred to to calculate the adjustment value for the alignment in the longitudinal direction.

An embodiment in which cyan is a basis will be described below. The calculation of the setting value for the upper ink jet head 407 is carried out in the same manner as that of the previous embodiment. The setting value for the upper ink jet head 408 for magenta will be described below.

In Fig. 25A and Fig. 25B, the line 451 or the line 453 is recorded by the ink jet head 403 for cyan, and the line 452 or the line 454 is recorded by the ink jet head 408 for magenta. The spectral characteristic of cyan is (R, G, B) = (0, FF, FF), while the spectral characteristic of magenta is (R, G, B) = (FF, 0, FF). When there is no deviation between the heads, which represents agreement, the signal detected by the sensor 416 is as shown in Fig. 39-41. That is, the spectral characteristic of the dot coverage recording is (R, G, B) = (80, 80, FF).

When the dot recorded by the upper ink jet head 408 for magenta deviates upward by one pixel, the spectral characteristic of the image recorded by the sensor 416 is as shown in Fig. 42-44. When the position of the upper ink jet head 409 for yellow and the position of the lower ink jet head 406 for yellow are the same, the signal is as shown in Fig. 45-47. When the recording position of the upper ink jet head 409 for yellow deviates upward, the signal is as shown in Fig. 48-50.

Even when the position of the upper ink jet head 410 for black and the position of the lower ink jet head 406 are the same, the signal is as shown in Fig. 51-53. When the recording position of the upper ink jet head 410 for black deviates upward, the signal is as shown in Fig. 54-56. In this way, using the spectral characteristic for each color component, it is possible to judge the positional deviation of each upper ink jet head based on the lower ink jet head 403 for cyan. Thereby, the alignment adjustment of each of the upper and lower heads in the longitudinal direction can be carried out according to the judged value.

While in the foregoing embodiment the adjustment value of the position of the upper ink jet head is determined with respect to that of the lower ink jet head in the ink jet heads arranged at two stages of the lower and upper sides, it is also advantageous that for each of the ink jet heads the adjustment value for the longitudinal alignment can be calculated in the same manner.

While in the foregoing embodiment the recording unit is formed by four color heads of cyan, magenta, yellow and black, it will be understood that this invention is not limited to such an embodiment, but the use of other color inks allows the longitudinal alignment to be adjusted in the same manner.

For example, a general-purpose scanning device can also be used instead of the sensors 415, 416 to measure the deviation.

While in the previously described embodiment, the signal read by the sensors 415, 416 is processed in the calculation unit 421 to determine an adjustment value corresponding to the deviation, it is also estimated that the signal is processed in a calculation unit which is spaced from the recording unit, and the adjustment value of the longitudinal alignment is transmittable to a calculation unit within the recording unit through any of a variety of communication means.

This embodiment is shown in Fig. 57.

In the same figure, reference numeral 414 denotes a recording medium for recording the image, 502 denotes a recording medium for recording a specific pattern for calculating the alignment adjustment value, and 503 denotes a scanner for reading the pattern recorded on the recording medium. Reference numeral 504 denotes a second calculation unit for calculating the adjustment value of the longitudinal alignment by receiving a reading result of the pattern recorded on the recording medium 502 output from the scanner 503. 505 denotes a main control unit having a first calculation unit 421 (see Fig. 21) for controlling the entire recording unit. 506 denotes a motor control unit for driving the carriage motor. ator 507 for scanning control of the recording head. 507 denotes the carriage motor for scanning drive of the recording head. 403 to 406 denote ink jet heads for the respective colors which are arranged on the lower side, and 407 to 410 denote ink jet heads for the respective colors which are arranged on the upper side and are the same as described above with reference to Fig. 20.

Using the inkjet heads 403 to 410, a pattern for calculating the longitudinal alignment adjustment value is recorded on the recording medium 502. And this pattern is read by the scanner 503 and calculated in the second calculation unit 504 to determine the longitudinal alignment adjustment value. The adjustment value thus calculated is transmitted to the first calculation unit 421 of the main control unit 505 via a communication cable for connection between the main control unit 505 and the second calculation unit 504. By adjusting the longitudinal alignment based on the transmitted longitudinal alignment adjustment value, image recording can be carried out in a state in which the longitudinal alignment of the upper and lower inkjet heads is the same.

It is to be noted that the feeding amount is changeable depending on the recording medium such as the material of the cloth and the type of the image. In this case, the changed feeding amount is transmitted to the main control unit of the recording unit through the transmission means (input from the control unit or input via communication from the cloth feeding unit), and the main control unit can control the reading position to adjust the longitudinal alignment according to the changed feeding amount of the cloth. With this means, recording with the variable feeding amount can be carried out without generating an overlap or a gap between the recorded images. It should be noted that the present invention is applicable to a system having a plurality of devices as well as to a unit having one device. It is also a matter of course that the present invention is also applicable to the cases in which a program for carrying out the invention is supplied to the system or unit.

As described above, according to this embodiment, a pattern for detecting the deviation of the longitudinal alignment is recorded and electrically read to calculate the adjustment value, and the reading position of the recorded data stored in the memory is changed according to the calculated adjustment value, whereby the longitudinal alignment can be automatically carried out. Thereby, it is possible to record a high quality image without generating false colors caused by the deviation of the arrangement position of each ink jet head.

As described above, according to the present invention, it is possible to precisely and easily adjust the recording position at which a plurality of recording heads are operative during recording.

The embodiments described above lead to excellent effects, especially with an ink jet recording head or in a recording device of the recording system based on generating fine ink droplets with heat energy of the various ink jet recording systems.

In view of the typical structure and the operating principle, a system which applies the basic principle described in US Patent Documents No. 4,723,129 and No. 4,740,796 is preferred. This system is applicable to both the so-called on-demand recording system and the continuous operation recording system. In particular, the case of on-demand recording systems effectively because by applying at least one drive signal which causes a rapid temperature rise above the nuclear boiling point in accordance with the recording information to the electrothermal conversion devices arranged corresponding to the substrates or the liquid channels which accommodate a liquid (ink), the heat energy is generated in the electrothermal conversion devices to cause film boiling on the heat active surface of the recording head and consequently the bubbles in the liquid (ink) can be generated in accordance with the drive signals in a ratio of 1:1. As the bubble grows and shrinks, the liquid (ink) is discharged through an ejection opening and at least one droplet is generated. By generating the drive signals in the form of pulses, the growth and shrinkage of the bubbles can be caused instantaneously and appropriately to achieve the ejection of the liquid (ink) in a more preferable manner with a quick response.

As the drive signals having such a pulse shape, those described in U.S. Patent Documents No. 4,463,359 and No. 4,345,262 are suitable. Furthermore, excellent recording can be carried out using the conditions described in U.S. Patent Document No. 4,313,124, and this invention relates to the temperature rise rate of the above-mentioned heat-active surface.

With respect to the structure of the recording head, in addition to the combination of the ejection nozzle, the liquid passage and the electricity-heat conversion means (straight liquid passage or rectangular liquid passage) as explained in the above-mentioned respective specifications, the structure as explained in the specifications of U.S. Patent Document No. 4,558,333 or No. 4,459,600 with the structure in which the heat active portion is arranged in the curved region is also included in the present invention. Furthermore, in the present For the present invention, the structure described in Japanese Patent Laid-Open No. 59-12367 is also effectively applicable, the structure using a common slot for a plurality of electricity-heat conversion devices as the discharge section of the electricity-heat conversion device, or Japanese Patent Laid-Open No. 59-138461 which describes the structure in which the opening for absorbing the pressure wave of the heat energy is corresponding to the discharge section.

Furthermore, as the recording head of the full-line embodiment having a length corresponding to the maximum width of a recording medium that can be printed by the recording apparatus, either the structure that forms the length by a combination of a plurality of recording heads as disclosed in the above-mentioned descriptions or the structure as an integrally formed recording head is usable.

Furthermore, the present invention is effective for a recording head of the freely replaceable chip type which allows electrical connection with the main body or supply of ink from the main body by being mounted on the main body, or for a recording head of the cartridge type in which an ink tank is integrally mounted on the recording head.

Also, adding a recovery means for the recording head, a preliminary auxiliary means, etc. to the structure of the recording apparatus of the present invention is preferable because the effect of the invention can be made more reliable. Specific examples thereof may include, for the recording head, capping means, cleaning means, pressure generating or suction means, electricity-heat converting means or other types of heating elements or preliminary heating means according to a combination of these. It is also effective to carry out reliable recording, to perform a preliminary mode which performs unloading separately from recording.

Furthermore, the present invention is extremely effective in the recording mode of the recording apparatus, not only in the recording mode of only one primary color such as black, etc., but also in an apparatus provided with at least one of a plurality of different colors or the full color by color mixing, wherein the recording head may be constructed either integrally or as a combination of a plurality.

Although the ink has been considered as a liquid in the above-described embodiments, the ink can be made into a solid state below room temperature as long as the ink is softened or liquid at or above room temperature or is liquefied when a recording signal common in the ink jet device is output to control the viscosity of the ink within a certain range of reliable ejection by controlling the temperature of the ink in a range of 30°C to 70°C.

In order to prevent the temperature rise due to the heat energy by using the heat energy as the energy for the state change from solid to liquid or to prevent the evaporation of the ink when using the ink which becomes solid when left, the ink having a property of liquefying only when heat energy is applied, such as liquefying when heat energy is applied according to a recording signal so that the liquid ink is ejected or can solidify before reaching a recording medium, can be used, which is also applicable to the present invention. In such a case, the ink can be held as a liquid or as a solid in recesses or through holes of a porous substrate which are in opposite the electro-heat conversion means as described in Japanese Patent Application Laid-Open No. 54-56847 or No. 60-71260. The most effective method for ink ejection as described above in the invention is based on film boiling.

Furthermore, a recording apparatus according to the invention is applicable integrally or separately as an image output terminal in an information processing apparatus such as a word processor or a computer as described above, a copying machine in combination with a reading device or a facsimile terminal having transmission and reception capabilities.

In the embodiments described above, when fabric is used as a recording medium, pretreatment or posttreatment of the fabric can be carried out as required, and an embodiment having these processes is considered to fall within the scope of the invention. The pretreatment and posttreatment are described below.

In particular, the fabrics intended for inkjet textile printing must have the following properties:

(1) Coloring with the ink in sufficient density,

(2) high drying speed of the ink,

(3) Drying of the ink on the fabric,

(4) slight irregular bleeding of the ink on the fabric,

(5) excellent transport characteristics in the device.

In order to meet these requirements, the fabrics can be pretreated according to the invention if necessary. For example, in Japanese Laid-Open Publication No. 62-53492, several types of fabrics having the ink-receiving layer are described, and in Japanese Patent Document No. 3-46589, fabrics are proposed which have a reduction in inhibitor or alkaline substances. One embodiment of such a pretreatment comprises treating the tissues with a selected substance, an alkaline substance, water-soluble plastic, synthetic plastic, water-soluble metal salt, urea and thiourea.

Examples of the alkaline substance are alkali metal hydroxide such as sodium hydroxide and potassium hydroxide, amines such as mono-, di- or triethanolamine, and carboxylic acid or alkali metal bicarbonate such as sodium carbonate, potassium carbonate and sodium bicarbonate. They also include metal salt of an organic acid such as calcium acetate and barium acetate, ammonia and ammonium compounds. Sodium trichloroacetate, which becomes an alkaline substance under the action of steam and heat, is also usable. A particularly preferable alkaline substance for use in coloring with reactive dye may be sodium carbonate and sodium bicarbonate.

Examples of water-soluble plastic include starch substances such as corn and wheat flour, cellulosic substances such as carboxymethylcellulose, methylcellulose and hydroxyethylcellulose, polysaccharides such as sodium alginate, gum arabic, locust bean gum, tragacanth gum, guar gum and tamarind seed, protein substances such as gelatin and casein, and natural water-soluble substances such as tannin and lignin.

Examples of synthetic plastic also include polyvinyl alcohol mixtures, polyethylene oxide mixtures, acrylic acid-based water-soluble plastic and maleic anhydride-based water-soluble plastic. Of these, polysaccharide plastic and cellulose plastic are preferable.

Examples of the water-soluble metal salt include compounds having a pH of 4 to 10 which form typical ion crystals, such as halides of alkali metal and alkaline earth metal. Typical examples of such Compounds which include alkali metals are, for example, NaCl, Na₂SO₄, KCl and CH₃COONa, and of alkaline earth metals are, for example, CaCl₂ and MgCl₂. Of these, the salts of Na, K and Ca are preferable.

The method of pretreating the fabrics to absorb any of the above-mentioned substances is not specifically limited, but may normally be any of dipping, tamponing, coating and spraying methods.

Furthermore, since the textile printing ink applied to the fabric for ink-jet textile printing can only adhere to the surface of the fabric in the jetted state, it is preferable to subsequently carry out a post-treatment, a reaction fixing process (dyeing process) of the dye to the fibers. Such a reaction fixing process may be any of the conventional, well-known methods, such as a steaming process, an HT steaming process or a heat-fixing process, and when the fabric is not treated with an alkaline compound, an alkali pad steaming process, an alkali cloth base steaming process, an alkali shock process and an alkali cold fixing process are used.

Furthermore, the removal of the unreacted dye and the substances used in the pretreatment after the reaction fixing process can be carried out by washing according to a conventional, well-known method. Note that a conventional fixing process combined with washing is preferably used.

In the present invention, the examples of the recording medium include cloths, wallpapers, papers, OHP recording media and the like.

It should be noted that the fabrics in this invention include all woven and nonwoven fabrics, regardless of the material, weaving and knitting.

The wall coverings in this invention include papers, fabrics and wall panels made of synthetic plastics such as polyvinyl chloride.

The printed material, which has been subjected to the above-mentioned additional treatments, is then divided into pieces of a desired size. The pieces are subjected to a finishing process such as sewing, bonding and solvent welding to produce the final products, e.g., garments such as one-piece or two-piece garments, neckties and bathing suits or trunks, bed covers, sofa covers, handkerchiefs and curtains. Fabrics made of cotton or silk and other materials, for example, are processed into clothes and other articles, e.g., by sewing as described in the "MODERN KNITTING AND SEWING MANUAL" published by Seni Journal (Fiber Journal), SOEN by Bunka Shuppan and many others.

Claims (21)

1. An ink jet recording apparatus for recording an image by scanning recording heads which are movable relative to the recording medium, the apparatus comprising: - a first ink jet recording unit (31) which is arranged in an access-side position relative to the transport direction of the recording medium, and a second ink jet recording unit (31) which is arranged in a downstream position, marked by - a drying device (34, 35) for drying the ink in a recording area in which, in the operational state, a recording is carried out on the recording medium by the first ink jet recording unit, wherein the drying device (34, 35) is arranged between the first ink jet recording unit and the second ink jet recording unit, and - a recording control device (2) for controlling the second ink jet recording unit to further perform the recording in at least the recording area dried by the drying device. 2. Ink jet recording apparatus according to claim 1, wherein a pretreatment device for applying a pretreatment agent to the recording medium is arranged on the access side of the first ink jet recording unit. 3. An ink jet recording apparatus according to claim 1 or 2, wherein said recording control means controls the execution of the multi-value recording in the recording area under use of the first ink jet recording unit and the second ink jet recording unit. 4. An ink jet recording apparatus according to claim 1, 2 or 3, wherein a plurality of recording heads are arranged, at least one of which is a recording head for ejecting a color ink having a lower density than any other ink. 5. Ink jet recording apparatus according to one of the preceding claims, wherein the drying device comprises a blower device which is directed towards the recording area of the recording medium. 6. Ink jet recording apparatus according to one of the preceding claims, wherein the drying device comprises a drying device which is arranged on the back of the recording medium. 7. An ink jet recording apparatus according to any one of the preceding claims, wherein the recording control means controls the first ink jet recording unit to intermittently record a part of the image data and controls the second ink jet recording unit to record the remaining image data not recorded by the first ink jet recording unit in the recording area dried in the drying section for supplementary recording. 8. An ink jet recording apparatus according to any preceding claim, wherein each of the first ink jet recording unit and the second ink jet recording unit has a recording head for ejecting ink, the recording head being an ink jet recording head having a thermal energy conversion element for generating thermal energy acting on the ink so that the ink is ejected using the thermal energy. 9. An ink jet recording apparatus according to any one of the preceding claims, wherein the control means is adapted to control the first unit and the second unit so that the first ink jet recording unit records at a density which is less than a predetermined final recording density and thereafter the second ink jet recording unit effects recording to supplementarily complete the predetermined final recording density. 10. Ink jet recording apparatus according to one of the preceding claims, wherein the transport device (37, 47, 49) is arranged to discontinuously transport the recording medium to the recording units. 11. Ink jet recording method for carrying out recording by ejecting the ink onto a recording medium by means of sequentially arranged ink jet recording devices, characterized by the steps: - creating a recording area with a first ink jet recording part on the recording medium, - drying the ink in the recording area by means of a drying device (34, 35), and - forming a second ink jet recording part in at least the recording area in which the ink is dried. 12. An ink jet recording method according to claim 11, wherein the ink is dried by a blower device directed toward the recording area of the recording medium. 13. The ink jet recording method according to claim 11 or 12, wherein the ink is dried by a drying device arranged on the back side of the recording medium. 14. The ink jet recording method according to any one of claims 11 to 13, wherein a part of the image data to be recorded is intermittently recorded in the first ink jet recording part, and the remaining image data which is not recorded in the first ink jet recording part is recorded in the second ink jet recording part. 15. An ink jet recording method according to any one of claims 11 to 14, further comprising a step of fixing the ink of the recording area on the recording medium after forming the second ink jet recording part. 16. The ink jet recording method according to claim 15, further comprising a step of washing the recording medium after the fixing process. 17. An ink jet recording method according to any one of claims 11 to 16, further comprising a step of treating the recording medium to apply a pretreatment agent to the recording medium prior to recording by ejecting the ink. 18. The ink jet recording method according to any one of claims 11 to 17, wherein the recording medium is cloth or paper. 19. An ink jet recording method according to any one of claims 11 to 18, wherein the first ink jet recording part has a density lower than a predetermined recording final density and the second ink jet recording part effects recording to supplementarily complete the predetermined recording final density. 20. The ink jet recording method according to any one of claims 11 to 19, wherein the recording material is divided into pieces each having a desired size on and a finishing treatment is carried out on the divided pieces. 21. The ink jet recording method according to claim 20, wherein the finishing treatment is sewing.